By Rachel Wulff

SACRAMENTO (CBS13) — More than 2,800 members of the Sacramento City Teachers Association are getting ready to go on strike for the first time in 30 years.

Sacramento City teachers, substitutes, nurses and psychologists are hard at work, prepping not to be at work Thursday. They are planning a one-day strike over a promise made in their last contract agreement over the use of health care savings.

READ MORE: Electra Fire: Firefighters Strengthening Control Lines, Some Amador County Evacuation Warnings Downgraded

“The district is reneging on that agreement,” said Nikki Milevesky, the VP of SCTA.

The union wants to use the health care savings for students and the school district wants to use the money to help reduce a $35 million budget deficit. The district says a strike could push it closer to a state takeover.

READ: Sacramento City Finalizes Schedule, Keeps First Day Of School As Is

READ MORE: Modesto Girl, 15, Shot In Bed After Gun Goes Off In Garage Nearby; Suspect Arrested

CBS13 did the math: There are 42,500 students in Sac City schools and attendance during a strike typically is 30%. If that happens Thursday, the state will only give the district $708,000 for their academic daily allowance instead of $2.3 million.

There is also the added cost of $500 a day for teacher replacements. The district says it has recruited replacements but wouldn’t say how many.

Alex Barrios, the communications director for the superintendent, said, “Right now we are still processing those replacements teachers we feel we have enough to get through school on Thursday.”

MORE NEWS: Suspect Arrested In Stockton Shooting That Left Man, 50, Dead 

The school district says there are also security costs associated with a strike. How much will go toward teacher replacements? They won’t know until Friday.